Actor and former California governor Arnold Schwarzenegger became the latest high-profile party member to withdraw his support after video footage emerged which showed the Republican nominee making crude comments about women.

He also told the Wall Street Journal there was "zero chance I'll quit" in the battle with Democratic rival Hillary Clinton.

Republican presidential candidate Donald Trump. Photo: AP

The comments came as a growing number of Republican figures urged Mr Trump to leave the race for the White House after a video surfaced which captured him making vulgar and sexually charged comments about women.

The Terminator actor admits that he has been "conflicted" by the election and went on to say that for the first time since he became a citizen in 1983 he is not going to vote for the Republican candidate for President.

Picture @Schwarzenegger

Mr Trump said he has also been getting calls of support after the footage dating from 2005 emerged.

Mrs Clinton called Mr Trump's remarks "horrific".

She said in a Twitter message: "We cannot allow this man to become president."

Republican leaders from Utah to Alabama called on Mr Trump to leave the presidential race as the party struggled to grapple with the crisis.

However, US House Speaker Paul Ryan and various other high-profile Republicans refused to abandon their nominee, who has long faced criticism from within his own party, but never to this degree.

Frustration turned to panic across the party with early voting already under way in some states, and with and election day just one month away.

In a videotaped apology, Mr Trump declared "I was wrong and I apologise" after being caught on tape bragging about aggressively groping women in 2005.

He also defiantly dismissed the revelations as "nothing more than a distraction" from a decade ago and signalled he would press his presidential campaign by arguing that Mrs Clinton has committed greater sins against women.

"I've said some foolish things," Mr Trump said in a video posted on his Facebook page early on Saturday.

"But there's a big difference between the words and actions of other people. Bill Clinton has actually abused women and Hillary has bullied, attacked, shamed and intimidated his victims."

Mr Trump addressed what was arguably the most difficult day of his candidacy on Twitter later on Saturday morning: "Certainly has been an interesting 24 hours!"

"The only good news is that in 30 days Trump will be back to being just a former reality TV star like the Kardashians, and Republican candidates across America will no longer be asked to respond to his stupid remarks."

Some Trump loyalists defended their nominee. "I still have my Trump sign on my yard and everybody on my street does too," said Pennsylvania party chairman Rob Gleason. "It's business as usual, with door-knocking today."

He went on: "I don't agree with what was said - it's not a good thing to be saying." But he added: "campaigns are filled with lots of ups and downs".

In the tape obtained by The Washington Post and NBC News, Mr Trump is heard describing attempts to have sex with a married woman. He also brags about women letting him kiss and grab them because he is famous.

"When you're a star they let you do it. You can do anything," he says in the previously unaired comments. He adds seconds later: "Grab them by the p****. You can do anything."

Alabama representative Martha Roby said Mr Trump's newly disclosed comments make him "unacceptable" for the presidency.

Mr Trump should "step aside and allow a responsible, respectable Republican to lead the ticket," she said in a statement.

House Speaker Mr Ryan said he was "sickened" by Mr Trump's remarks, and revoked an invitation for the nominee to appear at a party event in Wisconsin. But Mr Ryan stopped short of withdrawing his endorsement.